Turbine



H. H. WAIT TURBINE June 25, 1929.

Fi led Feb. 20, 1923 INVENTOR. flay/7f m5 ATT RNEY.

Patented June 25, 1929.

UNITED STATES HENRY H. WAIT, OF ANDERSON, INDIANA.

TURBINE.

Application filed February 20, 1923. Serial No. 620,263.

It is the object of my ,ivention to improve the construction ofturbines. More specifically, .it is the object 0t my invention toprovide an efiicient mounting of the stationary blades in thediaphragms, whereby the blades are held lirmly and properly in place ata minimum of cost and a maximum of rigidity inconstruction andetliciency in action; to provide non-expanding guide passages in appropriate diaphragms, by blades which not only permit economicalconstruction but provide eflicieut stream-line passages and in additionare of unusually strong construction; and to provide a beam andcantilever dia phragmconstruction of great strength but light weight.

The accompanying drawing illustrates my invention Fig. 1 is afragmentary elevation of a diaphra gm through which there arenon-expanding steam passages, showing the lower half of the diaphragmcomplete; Fig. 2 is a sectional development on the line 2-2 of Fig. 1;Fig. 3 is a section on the line 3-3 of Fig. 2; Fig. -l is an enlargedradial section through an outer part of a rotating element and theadjacent diaphragms, to show the ammlar ribs.

The turbine comprises a casing 20 carrying a plurality oi diaphragms 21which divide the turbine into a plurality of stages, for each of whichthere is a turbine wheel 23. The turbine wheels 23 are provided at ornear their periphery with suitable blades 2% mounted in a suitablemanner; but as the de tails of the moving blades and their mounting form.110 part of my present invention they are not illustrated in detail.One or more of the diaphragms 21 may have expanding steam-passages, suchas-shown at the left of Fig. l; while other diaphragms may havenon-expanding steam-passages as indicated at the right of Fig. l.

Steam is supplied to the hi gh-pressurc end of the machine by anydesired means, the steam passing successively through the tur binewheels and diaphragms in the usual manner.

The non-expanding passages such as are present in the diaphragmillustrated at the right of Fig. 4t are provided by blades which aremounted on the edges of the diaphragm 21 between it and a clamping ring46. The blades 45 are held in place between the edge of the tiliaohragman l the clamping ring; by lial :inenibers while... .l inward throughthe clamping ring, through the respective blades, and into the edge ofthe diaphragm, is clear from Fig. 1. Some of these "adial members arescrews d7; but there may be less of these than the entire number ofblades, and for the remaining blades the radial members are pins -l8driven in place. The pins d8 preferably have threaded holes ll) in theirouter ends, to receive a suitable screw for pulling the pin out whendesired. In addition to these through members 47 and 418, each blade41:5 also preferably has a dowel pin 50 between it and the edge of thediaphragm, which dowel pin is eccentric with respect to the throughmembers 47 or 48, so that it co-operates therewith to prevent the bladefrom turning.

The blades 41:5 may or may not extend the tul l. circumference of thediaphragm. On the diaphragm illustrated. in Fig. 1, which is a diaphragmadapted for use near the highpressure end of the turbine, the bladingextends only over part oi the circumference, and for the ren'iainder ofthe lower half of the diaphragm the annular blading space is sol.- idlytilled. by an arc-shaped strip 51 which is clamped similarly to theblades 45 between the edge oil the diaphragm and the clamping ring 46;and in that diaphragm the upper halt of the diaphragm may extend outradially as far as the outer edge of the clamping ringflti provided onthe lower hall. In the diaphragm or diapl'n'agms near the lowpressureend of the turbine, however, the bl ading normally extends for thecomplete circumterence, in which *ase both halt diaphragnns are providedwith clamping rings L6, and there is no strip 51. In this latter r-ase,the diaphragm is completely carried by the rings 46; and the supportgiven the diaphragm from such rings through the blades d5, screws 47,and pins 48 is su'l'licient to with stand the ditlerential steampressure between the two sides of the diaphragm, without requiring anyadditional supporting posts for the diaphragm. By reason of this, theentire steam-passages between. the blades may be utilized, and therewill be no interruption in the flow of steam around the circumference,thereby avoiding in the current of steam through the revolving bladesthese interruptions which would cause acceleration and decelerationlosses at the blades where such inoccur.

a 5 viewed radiall' thielr at the in ar plan. at

blade-face is convex at the middle part, with substantially straightflaring faces toward the edges. Viewing the clamping rmg 416 and theedge of the diaphragm 21 in radial section, as in Fig. 3, the outer edgeof the diaphragm is substantially straight, paralleling the turbineaxis, preferably with a slight chamfer 56 on the high-pressure side, anda fsli 'ht flare 57 on the low- )ressure side and still viewing it inradial section,the clamping ring l6 on its inner or blade-engaging face58 is of smaller diameter on the highpressure side than on thelow-pressure side,

and is concavely curved outward from the small-diameter dimension 011the high-pressure side almost to the larger diameter lowpressure side,though preferably for a small distance inward from the lowpressure sideit'may have a straight portion 59. Those faces of the blades 45 and ofthe strip 51 which engage the edge of the diaphragm and the inner faceof the clamping ring are properly shaped to fit such faces of thediaphragm and clamping ring; save that if desired the blade 45 or strip51 need not follow the chamfer 56. Each steam passage 60 betweenadjacent blades 15 is bounded by the concave face of one blade and theconvex face of a neighboring blade, and by the outer edge face '55 ofthe diaphragm and the inner face 58 of the clamping ring. This steampassage :60, viewed tangentially as in Fig. 3, flares from thehigh-pressure side to the low-pressure side; but viewed radially itconverges from the high-pressure side to the low-pressure sidethroughout the length of the adjacent concave blade-face. This radiallyviewed convergence is preferably slightly greater thanthe"tangentially-viewed divergence, when it is desired to'provide a dropin pressure of the steampass'ing through the diaphragm, as thereby thecross-section of such steam passage is made slightly convergent as awhole, and thus forms a converging nozzle. Such a nozzle is preferablyused in the last diaphragm; However, if substantial'lyno pressure-dropis desired in the passage of steam through a diaphragim as is the casewith the first diaphragm, the steam pas sage may be of substantiallyconstant area throughout. This may be obtained by suitably arranging theangles and profiles; and may be obtained to a certain extent with thesame blades and the same clamping rings, by turning the blades slightlyon their axes and shifting axially of the turbine the line of screws andpins 4748 with relation to the faces of the diaphragm, so that thedischarge edges of the blades are kept substantially at the dischargeface of the diaphragm: in which latter case the receiving edges of theblades may be cut oli to make them flush with their face of thediaphragm and of suitable angle to receive the steam.

Vith this shape of passage, I am able to avoid in the steam passage anypreliminary expansion and subsequent recontract ion, with its consequentlosses, such as occur with many types of blades. lVith my blades, anysteam passage through the diaphragm does not contract at any point afterhaving expandcd.

In a diaphragm, such as that illustrated at the left of Fig. l, whereexpanding steampassages are desired, these may be provided by blades 71held in place on the periphery of the associated diaphragm by means of aclamping ring (58 similar to the ring 4-6 which holds in place theblades 15 forming non-expanding steam passages.

Each diaphragm 21 must withstand a considerable ditlerential pressurebetween its two sides, sometimes amounting to several tons. To take careof this, with a reasonably light diaphragm structure, and to provideample room for the rotating shaft at the center of the diaphragn'i, Iuse the structure shown in Fig. 1. is a web; but built into this web andsuperposed upon each half of it are a plurality of intersecting ribs orbeams 75, and cantilevers 76, the beams extending along chords of thecircle of the diaphragm, and the cantilevers extending inward froin thecircumference of the circle to meeting points with the beams. In thesimple structure shown, the beams or ribs 75 extend across each halldiaphragm obliquely to each other to cross each other as close to theshaft opening as possible, one end of each beam extendingto thecircumferemc as near as possible to the intersection of thecircumference with the joint between the two halves of the diaphragms;and the cantilever 76 in each half-diapl'n'agm extends inward from thecircmnference of the diaphragm at a point from the joint, through thejunction of the beams 75, to the shaft opening. This network arrangementof beams and cantilevers superposed on the web of the diaphragm makes astructure which is both strong and light.

The turbine wheels are also webs of strength, usually with a few holestherethrough to equalize the pressure on the two sides of the web andprevent end thrust. The revolving blades project axially slightly beyondthe ring of the wheel. On the wheel web near the edge thereof are one ormore annular ribs on each face, the ribs on the two faces preferablybeing opposite each other. As shown, there are two such annular ribs oneach face of each turbine wheel, but this number is variable either wayas desired.

These concentric ribs 80 project axially a very slight distance furtherthan do the blades 24;, so that in case of any e'ndwise movement of therotating element it is these ribs 80 which strike the adjacent faces 81of the diaphragms 21. This prevents the rotating blades from strikingthe stationary blades on any such endwise movement, and cl'licientlyprotects both sets of blades. Further, because the ribs 80 arecon'iparatively narrow, there will be comparatively little injury fromfriction between them and the faces Slof the diaphragms 521 if the ribsdo rub on such faces.

In addition to this function of protecting the blades, the ribs 80 haveadditional functions. In the first place, they serve materially tostiffen the rotating wheelwveb. In the second place, they serve asbattles to break up the currents in the surrounding medium caused by therotation of the wheel; as in any such rotating wheel the steam inengagement with the surface of the rotating member is entrained andthrown outward, and this involvcs an inflow along the surface of theadjacent diaphragms. These rotational losses due to this circulatingfluid-flow increase approximately as the fifth power of the diameter. Byproviding the ribs 80, this flow is broken up, into a much smallercentral section and one or more comparatively small outer annularsections, the number depending on the number of ribs 80, on each side ofthe rotating wheel web; and this results in a material reduction in therotational losses from this cause.

I claim as my invention:

1. In a turbine, the combination of a casing, a diaphragm dividing saideasing into stages for separate turbine wheels, a clamping ring radiallyspaced from said diaphragm, a series of blades between said clampingring and the edge of the diaphragm and fitting against both, and meansfor clan'iping said clamping ring, blades, and diaphragm together, oneof the blade-abutting faces of said clamping ring and diaphragm beingconcavely curved axially of the diaphragm.

2. In a turbine, the combination of a casing, a diapln'agm dividing saideasing into stages for separate turbine wheels, a clamping ring radiallyspaced from said diaphragm, a series of blades between said clampingring and the edge of the diaphragm and fitting against both, and meansfor clamping said clamping ring, blades, and diaphragm together, theblade-abutting faces of said diaphragm and clamping ring beingrelatively flaring toward the low-pressure side of the diaphragm, andone of said faces being concavely curved axially of the diaphragm.

In a turbine, the combination of a easing, a diaphragm dividing saideasing into stages for separate turbine wheels, a clamping ring radiallyspaced from said diaphragm, a series of blades between said clampingring and the edge of the diaphragm and fitting against both, and meansfor clamping said clamping ring, blades, and diaphragm together, theinner face of said clamping ring fitting upon said blades and beingaxially COlICtLVG.

cl. In a turbine, the combination of a casing, a diaphragm dividing saideasing into stages for separate turbine wheels, a clamping ring radiallyspaced from said diaphragm, a series of blades between said clampingring and the edge of the diaphragm and fitting against both, and meansfor clamping said clamping ring, blades, and diaphragm together, theinner face of said clamping ring fitting upon said blades and beingaxially concave and of larger diameter on the low-pressure side than onthe high-pressure side.

In witness whereof, I have hereunto set my hand at Indianapolis,Indiana, this 19th day of February, A. D. one thousand nine hundred andtwenty-three.

HENRY H. VVAI'I.

